Well ventilated – Stop you yawning keep you awake
Well Lit – Either by lights or windows / No glare (I’ve got blackout curtains due to glare)
Comfy chair – Ergonomic if you work for hours and hours at a time

I’ve got a big wood & glass desk with a 29” monitor with two 21.5” monitors above it, one wall is red with a nice comfy sofa in the corner